Errors/Root Cause: Usually its due to Oracle memory and parameters sizing done incorrectly.

Workaround: 1. Check ADDM Report for the following * Wait time analysis for where the system is spending most of its time – this will narrow it down to memory or CPU * Any SQLs that are being run frequently and are consuming large percentage of memory or CPU – tune those SQLs * PGA, SGA sizing recommendations – size the instance based on these recommendations 2. Check the AWR report for the following: * SQLs tuning recommendations in the report * Memory tuning recommendations in the report 3. Oracle on a 32 bit Windows Server can address only up to 2G of physical memory. ie. SGA + PGA can only address up to 2G of physical memory. If the combined size exceeds this, TNS errors will start. Workaround is to implement the /3G switch in the Windows server (Metalink Note 371983.1), so that Oracle can address up to 3G of physical memory. The other option is to migrate to a 64 bit Windows Server. 4. Check the optimizer_index_cost_adj parameter. This should be set to a value lower than 100 (recommended 40). Having this parameter at 100 can lead to a lot of full table scans inspite of having indexes